I am not sure if I understand your question. It sounds like you would like to create a link in the footer of your website that looks like the "Powered by Backdrop" link that is already there.
Here is how I would do this:
- Go to admin/structure/layouts
- Click on Manage Blocks on the layout of your choice
For more information about layouts and templates:
- Go to the footer region and click on Add Block
- Give the block a name and put your link in the body of the block (you can center it there).
- Make the block reusable in case you need to use it in other layouts
I hope this is helpful. If I misunderstood your question, let me know.
NOTE: Ich sprechen etwas gut Deutsch. (if that helps)